1 String Compression III String
Medium 100
0.7% 2 Maximum Number of Ones Math Greedy Sorting Heap (Priority Queue)
Hard 98
0.7% 3 Reverse Nodes in k-Group Linked List Recursion
Hard 92
0.7% 4 Number of Islands Array Depth-First Search Breadth-First Search Union-Find Matrix
Medium 88
0.6% 5 LRU Cache Hash Table Linked List Design Doubly-Linked List
Medium 84
0.5% 6 Reverse Linked List Linked List Recursion
Easy 84
0.8% 7 Two Sum Array Hash Table
Easy 84
0.6% 8 Longest Substring Without Repeating Characters Hash Table String Sliding Window
Medium 84
0.4% 9 Valid Parentheses String Stack
Easy 79
0.4% 10 Palindrome Number Math
Easy 74
0.6% 11 Rotate Image Array Math Matrix
Medium 74
0.8% 12 Power of Two Math Bit Manipulation Recursion
Easy 74
0.5% 13 Reverse Bits Divide and Conquer Bit Manipulation
Easy 74
0.7% 14 Remove Nth Node From End of List Linked List Two Pointers
Medium 74
0.5% 15 Rectangle Overlap Math Geometry
Easy 74
0.5% 16 Linked List Cycle Hash Table Linked List Two Pointers
Easy 74
0.5% 17 Reverse String Two Pointers String
Easy 74
0.8% 18 3Sum Array Two Pointers Sorting
Medium 74
0.4% 19 Climbing Stairs Math Dynamic Programming Memoization
Easy 66
0.5% 20 Middle of the Linked List Linked List Two Pointers
Easy 66
0.8% 21 Implement Queue using Stacks Stack Design Queue
Easy 66
0.7% 22 Pow(x, n) Math Recursion
Medium 66
0.4% 23 String to Integer (atoi) String
Medium 66
0.2% 24 Majority Element Array Hash Table Divide and Conquer Sorting Counting
Easy 66
0.7% 25 Design Circular Queue Array Linked List Design Queue
Medium 66
0.5% 26 Count the Number of Fair Pairs Array Two Pointers Binary Search Sorting
Medium 66
0.5% 27 Trapping Rain Water Array Two Pointers Dynamic Programming Stack Monotonic Stack
Hard 66
0.7% 28 Count Array Pairs Divisible by K Array Hash Table Math Counting Number Theory
Hard 66
0.3% 29 Move Zeroes Array Two Pointers
Easy 66
0.6% 30 Swap Nodes in Pairs Linked List Recursion
Medium 56
0.7% 31 Serialize and Deserialize Binary Tree String Tree Depth-First Search Breadth-First Search Design Binary Tree
Hard 56
0.6% 32 Design Memory Allocator Array Hash Table Design Simulation
Medium 56
0.5% 33 Length of Last Word String
Easy 56
0.6% 34 Remove Duplicates from Sorted Array Array Two Pointers
Easy 56
0.6% 35 Trapping Rain Water II Array Breadth-First Search Heap (Priority Queue) Matrix
Hard 56
0.6% 36 Maximum Depth of Binary Tree Tree Depth-First Search Breadth-First Search Binary Tree
Easy 56
0.8% 37 Reverse Integer Math
Medium 56
0.3% 38 Course Schedule II Depth-First Search Breadth-First Search Graph Theory Topological Sort
Medium 56
0.6% 39 Is Subsequence Two Pointers String Dynamic Programming
Easy 56
0.5% 40 Permutations Array Backtracking
Medium 56
0.8% 41 Power of Four Math Bit Manipulation Recursion
Easy 56
0.5% 42 Merge Sorted Array Array Two Pointers Sorting
Easy 56
0.6% 43 Single Number Array Bit Manipulation
Easy 56
0.8% 44 Kth Largest Element in an Array Array Divide and Conquer Sorting Heap (Priority Queue) Quickselect
Medium 56
0.7% 45 Merge Intervals Array Sorting
Medium 56
0.5% 46 Subarray Sum Equals K Array Hash Table Prefix Sum
Medium 56
0.5% 47 Median of Two Sorted Arrays Array Binary Search Divide and Conquer
Hard 56
0.5% 48 Edit Distance String Dynamic Programming
Medium 56
0.6% 49 Find the Index of the First Occurrence in a String Two Pointers String String Matching
Easy 56
0.5% 50 Generate Parentheses String Dynamic Programming Backtracking
Medium 56
0.8% 51 Implement Stack using Queues Stack Design Queue
Easy 56
0.7% 52 Last Substring in Lexicographical Order Two Pointers String
Hard 56
0.4% 53 Merge k Sorted Lists Linked List Divide and Conquer Heap (Priority Queue) Merge Sort
Hard 56
0.6% 54 Container With Most Water Array Two Pointers Greedy
Medium 56
0.6% 55 Merge Two Sorted Lists Linked List Recursion
Easy 56
0.7% 56 Moving Average from Data Stream Array Design Queue Data Stream
Easy 56
0.8% 57 Longest Common Prefix Array String Trie
Easy 56
0.5% 58 Counting Bits Dynamic Programming Bit Manipulation
Easy 56
0.8% 59 Peak Index in a Mountain Array Array Binary Search
Medium 56
0.7% 60 Maximum Product Subarray Array Dynamic Programming
Medium 56
0.4% 61 Number of 1 Bits Divide and Conquer Bit Manipulation
Easy 56
0.8% 62 Unique Paths Math Dynamic Programming Combinatorics
Medium 56
0.7%